CZ9902653A3 - Purification of fatty acid polyol polyesters by making use of a mixing vessel with controlled agitation - Google Patents

Abstract

Process for processing polyol fatty acid polyesters includes the filling of the crude polyol polyester with a fatty acid-containing impurities and soaps and washing solution into mixing containers and dispersing the contents into a mixture. Processed the mixture is allowed to settle and split into two phases. First stage contains a polyol fatty acid polyester, a second phase contains washing solution, soap and dirt. Processed the fatty acid polyol polyester is produced herein procedure. Dirt soluble in wash solution, such as e.g. color matter, etc., are removable impurities the present process. The washing solution contains chelating contaminants such as trace impurities metals

Description

Technical field

The present invention relates to the purification of polyol fatty acid polyesters by mixing with a scrubbing solution in a controlled mixing vessel. Furthermore, the invention relates to the purified polyol fatty acid polyesters treated with the present process.

BACKGROUND OF THE INVENTION

The food industry has recently focused on the production of polyol fatty acid polyesters used as low-calorie fats in food products. The result of this trend is a constant demand for economically and efficiently advantageous production processes producing relatively high purity polyol fatty acid polyesters.

The production of a polyol fatty acid polyester consists in reacting the polyol with a lower alkyl fatty acid ester in the presence of a basic catalyst. Typically, polyols are well soluble in aqueous media, e.g., water, while lower alkyl esters of fatty acids are soluble in organic solvents. Therefore, it is usually convenient to use an emulsifier. a solvent, a phase transfer catalyst, or a mixture thereof, to allow physical contact between the polyol and the lower alkyl esters of the fatty acids, followed by a chemical reaction. The resulting fatty acid polyol polyester is soluble in organic media.

Thus, the polyol reaction product stream resulting in the formation of a polyol fatty acid polyester comprises other miscellaneous components in addition to the desired polyol fatty acid polyester. For example, they are residual reactants, i.e. unreacted lower alkyl fatty acid ester and / or unreacted polyol, emulsifier, solvent, phase transition catalyst and / or basic catalyst. In addition to said components, the product mixture may also contain reaction by-products itself. For example, in addition to the transesterification of polyol to polyol polyester.

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ΦΦ ΦΦ fatty acids undergo a number of side reactions. These include, for example, the cleavage of one of the reactants into two or more products and / or the starting reactants, catalysts, emulsifiers and solvents chemically react to undesired byproducts such as di- and triglycerides, beta-ketoesters, di-fatty ketones and unsaturated soaps. In addition, the starting compounds and other reactants often contain trace amounts of various materials, eg trace metals, which are particularly undesirable in the final products, such as food additives. Therefore, the reaction products of the polyol and the lower alkyl fatty acid ester contain, in addition to the desired product, the polyol fatty acid polyester, a number of undesirable components that must be removed to prepare a sufficiently purified polyol fatty acid polyester.

Separation procedures for purifying the product mixture in the preparation of polyol fatty acid polyesters are generally known in the art. U.S. Pat. Nos. 4,241,054, 4,517,360 and 4,518,771 to Volpenhein briefly discuss separation procedures for purifying a mixture of polyol fatty acid polyesters. Volpenhein broadly discusses distillation, washing, conventional refining processes or solvent extraction. However, the blend of polyol transesterification reaction products presents unique challenges. For example, polyol fatty acid polyesters are often used as low-calorie fats, of which trace amounts of materials unsuitable from a food point of view have to be removed, even if they do not affect the use of the product for non-food purposes. On the other hand, some degradation products of the starting reactants, such as caramelized by-products of polyol degradation, which are harmless from the food point of view, impart inappropriate color to the product and / or increase its calorific value and therefore have to be removed from the product mixture. A complex and highly variable blend of polyol transesterification products into polyol fatty acid polyesters is a real challenge and challenge in designing purification procedures.

Therefore, there remains a need for improved separation and purification processes for product mixtures in the production of polyol fatty acid polyesters, especially polyol transesterification by-products. More specifically, an economically advantageous and efficient separation process for removing water-soluble components, emulsifiers, trace metals and other undesirable components from the polyol fatty acid polyester product is desired.

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SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved purification process for isolating polyol fatty acid polyesters. It is an object of the present invention to provide an improved purification process of polyol fatty acid polyesters suitable as additives for food use.

In an embodiment of the present invention, the invention is directed to a method of purifying unrefined polyol fatty acid polyesters. The process comprises filling a crude polyol fatty acid polyester containing soaps and impurities into a mixing vessel. The wash solution is also filled into the mixing vessel and the contents are dispersed onto the mixture. Some of the soils and soaps pass from the raw polyester product mixture to the wash solution. The mixture was allowed to settle and split into two phases. The first phase contains purified polyol fatty acid polyester, the second phase contains soap and impurities in the wash solution. Another embodiment of the invention is directed to the purified polyol fatty acid polyesters prepared by the process described herein.

Another embodiment of the invention is directed to a process for the production of purified polyol fatty acid polyesters, which are prepared by reacting a polyol, a soap and a lower alkyl fatty acid ester, to produce a product mixture comprising a polyol ⁷ fatty acid polyester, soap and impurities. The process comprises filling the reaction product and the scrubbing solution into a mixing vessel and dispersing the reaction product with the scrubbing solution onto the mixture. The blend is formed by controlled mixing of the wash solution and unrefined polyester, which ensures optimal contact between the two phases, thereby promoting a massive transfer of impurities from the unrefined product mixture phase to the wash solution while avoiding stable emulsions. The next step of the process is settling, separating the mixture into two phases. The first phase comprises purified polyol fatty acid polyester, the second phase contains a wash solution. The settling is followed by phase separation.

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Another embodiment of the present invention relates to the use of a mixing vessel and dispersion of a wash solution with an unrefined blend of polyester products under controlled conditions that prevent the formation of a stable emulsion.

Detailed description

The present invention is explained in more detail below on specific embodiments. According to the present process for preparing the purification of polyol fatty acid polyesters, the unrefined polyol fatty acid polyester (crude polyol fatty acid polyester) is charged into a mixing vessel. Next, the wash solution and the unrefined polyol fatty acid polyester are fed into the mixing vessel and the wash solution is dispersed onto a mixture of the unrefined polyol fatty acid polyester and the wash solution. The composition comprises droplets having an average diameter preferably in the range of 5 to 3000 µm, more preferably 5 to 70 µm, most preferably 5 to 20 µm. After sufficient mixing, the mixture is allowed to settle into two phases, due to the natural immiscibility of the first phase, containing the purified polyol fatty acid polyester, with the second phase, containing the wash solution, soap and impurities.

All particle diameter sizes reported herein were measured on a Lasentech scanning laser detector. The Lasentech is a rectangular rectangular reflectance measuring system and includes a computer interface, a laser diode, detectors, a 10 m optical cable, and a test tube. The light beam from the laser diode travels through the optical cable to the tube. The light is concentrated at a very small point in the tube and passes through the sapphire window to the measured material, the light passing around the particles, in this case droplets, is scattered back. This light is concentrated and returned to the unit where the clock switches. As soon as the light passes the droplet, the backscatter is interrupted and the clock stops. By knowing the speed of the light beam and the time of the back pulse, the droplet diameter can be determined. For a given set of conditions, the average diameter size is calculated by dividing the total sum of the averages by the number of droplets measured.

As will be appreciated, unrefined polyol fatty acid polyester is commonly produced by reacting a polyol with a lower alkyl ester of a fatty acid. IN

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However, other processes for producing unrefined polyol fatty acid polyester are known in the art. Purified polyol fatty acid polyesters are used inter alia as low calorie fats in the food industry. The present purified polyol fatty acid polyesters are particularly useful for improved food grade purity.

By washing solution is meant solvents that, when mixed with an unrefined polyol fatty acid polyester under the conditions described herein, remove at least a portion of the impurities and soap contained in the unrefined composition. The wash solution typically comprises solvents such as water, methanol, acetone, and ethyl acetate. Water and aqueous solutions are preferred for the present process, due to the availability and cost, but other solvents are also suitable for the present purpose if, after mixing with the unrefined mixture, at least some of the impurities are separated.

The scrubbing solution optionally further comprises one or more additives, eg, a chelating agent chelating metals present in the unrefined polyol fatty acid polyester. The chelating agent binds to the chelating portion of the metals present in the unrefined polyol fatty acid polyester and passes into the wash solution. It will be appreciated that without the effect of the chelating agent, these metals would not pass into the wash solution, as shown in Example 4 below. The preferred chelating agent in the present invention is tripotassium citrate, and other possibilities will be apparent to those skilled in the art. The preferred chelating agent concentration in the present composition is less than 5.0 wt. relative to the wash solution. The washing solution should preferably contain less than 0.5 wt. impurities prior to contact with an unrefined polyol fatty acid polyester. Any impurity in the scrubbing solution may be considered to be of no significance in the removal of impurities from polyol fatty acid esters. Thus, the wash solution comprises soil removal solvents from unrefined polyol fatty acid polyester.

The term polyol fatty acid polyester includes any polyol as defined herein whose hydroxyl groups are esterified with carboxylic groups of fatty acids. The polyol is preferably esterified with four or more fatty acids. Preferred polyol fatty acid polyesters include sucrose esters

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49,994 containing an average of four, more preferably at least five, ester linkages per sucrose molecule, the fatty acid chain preferably containing 8 to 24 carbon atoms. As used herein, the term unrefined polyol fatty acid polyester is a composition comprising predominantly a polyol fatty acid polyester and impurities and / or soap as defined below before performing the present separation process. The amount and type of impurities and soap vary depending, inter alia, on the source of the polyol fatty acid polyester and the purification process if any has been included prior to filling the mixture into the mixing vessel according to the process of the present invention.

The term polyol includes any aliphatic or aromatic compound containing at least two free hydroxyl groups. For example, suitable polyols may be selected from the following classes of compounds: saturated and unsaturated, straight and branched chains of linear aliphatic compounds; saturated and unsaturated, cyclic aliphatic species including heterocyclic; or mononuclear and polynucleic aromatics including heterocyclic aromatics. Preferred polyols are hydrocarbons and non-toxic glycols.

Monosaccharides suitable for the present use are e.g. glucose, mannose, galactose, arabinose, xylose, ribose, apiosis, rhamnose, psicosis, fructose, sorbose, tagatose, ribulose, xylulose and erythrulose. Oligosaccharides suitable for the present use are, for example, maltose, kojibiosis, nigerose, cellobiose, lactose, melibiosis, gentibiosis, turanose, rutinose, trehalose, sucrose and raffinose. Polysaccharides suitable for the present use are, for example, amylose, glycogen, cellulose, chitin, inulin, agarose, zylanes, mannan, and galactans. Although sugar alcohols are not hydrocarbons in the narrow sense, naturally occurring sugar alcohols are so closely related to hydrocarbons that they can be considered as preferred substances for the present purposes. Natural sugar alcohols suitable for the present purposes are sorbilol, mannitol and galactitol.

The term impurity includes various components whose presence in the polyol fatty acid polyester purified according to the present process is undesirable. As will be appreciated further, some components, such as di- or triglycerides, may be insignificant, but undesirable (i.e., impurity) for a single use polyol polyesters of fatty acids for another use. E.g. di- and triglycerides are * 0 00 00 * · * 0 ··· 00 ··

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- 7,0000 calorie fats, their presence in the polyol fatty acid polyester used as low calorie fat is undesirable, so they are considered as impurities in this respect. Similarly, in the polyol polyester, fatty acids used in the food industry are undesirable trace metals if they are unsuitable for human nutrition. Other substances, such as degradation products of the starting reactants from the preparation of polyvinyl fatty acid polyesters, such as sucrose caramelization products, may be harmless and suitable for the average consumer. However, the caramelization products have an inappropriate color and / or adversely affect the viscosity of the polyol fatty acid polyester. Therefore, degradation products ^{7 are} also considered impurities, although they are generally harmless and edible. Thus, the term impurity represents all components that are not the desired polyol fatty acid polyester. Soap and lower alkyl esters of fatty acids will be discussed in more detail below.

Due to the side reactions occurring simultaneously with the transesterification, the product mixture contains, in addition to the polyol fatty acid polyester, a number of by-products which are also considered impurities. The most common are di-fatty ketones and beta-ketoesters, the removal of which is highly desirable and is conveniently performed with non-aqueous solvents. Fatty acids are often produced by hydrolysis of lower alkyl esters of fatty acids. Reaction of the fatty acid methyl ester with the catalyst produces unsaturated soaps, which are best extracted with an aqueous solution.

Other possible impurities ⁷ in the reaction mixture after preparation of the polyol fatty acid polyester are the reaction product (s) used to prepare them. The term reactant includes any component used in the preparation of a polyol fatty acid polyester. Suitable reactants are, but are not limited to, polyol, lower alkyl esters of fatty acids and / or glycerides, emulsifiers, catalysts ^7, and mixtures thereof.

The lower alkyl fatty acid ester is often reacted with the polyol to form a polyol fatty acid polyester. Complete esterification of the polyol typically requires the presence of a stoichiometric excess of lower alkyl fatty acid esters. However, an excess of lower alkyl fatty acid esters causes a significant concentration of residual lower alkyl fatty acid esters in the reaction product mixture. The residual lower alkyl ester of the fatty acid is not normally water soluble, i.e. in the preferred solvent of the present invention. Plus

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As the lower alkyl ester of the fatty acid is the reactive component of the preparation of the polyvinyl fatty acid polyester, the possibility of its isolation and recycling is desirable. Therefore, a lower alkyl ester of a fatty acid is usually not a component referred to as an impurity. A more detailed description of the direct recycling of lower alkyl fatty acid esters can be found in U.S. Pat. U.S. patent application Ser. No. 08/797/018, Attorney Docket Time 6506, entitled Lower Alkyl Ester Recycling In Polyol Fatty Acid Polyester Synthesis', incorporated herein by reference.

Lower alkyl fatty acid esters cannot normally be removed by aqueous solution extraction, although some of the lower alkyl esters and polyol fatty acid polyester inevitably pass into the wash solution. The lower alkyl esters of fatty acids are preferably separated from the polyol polyesters by thermal evaporation. The lower alkyl esters of fatty acids evaporate at a lower temperature than the polylic polyesters, but all of the lower-boiling impurities present in the product mixture evaporate with them. Therefore, to prepare sufficiently pure lower fatty acid alkyl esters directly recyclable to the polyol polyester synthesis, it is desirable to remove the maximum of soap and other impurities and to include a wash separation step according to the present process prior to the evaporation step.

Further, it is desirable to minimize the extent of hydrolysis resulting in the formation of free fatty acid during the present processing process. The free fatty acid resulting from the hydrolysis of the lower alkyl fatty acid esters is difficult to separate from the lower alkyl fatty acid esters due to the close vapor pressure values. To prevent more extensive hydrolysis during the wash, the pH of the wash solution / unrefined polyol fatty acid ester mixture must be maintained at a pH greater than

5.5 and avoid using acids. In addition, the processing time in the mixing vessel should not exceed 30 minutes, preferably 15 minutes. Thus, the present process can be used for the purification of a polyol fatty acid polyester as well as for the purification of lower alkyl fatty acid esters for recycling.

A preferred emulsifier for transesterifying a polyol to a polyol fatty acid polyester is an alkaline fatty acid soap. The term alkaline fatty acid soap or soap includes both saturated and unsaturated fatty acids containing 8 to 24 carbon atoms.

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Suitable alkali salts are, for example, lithium, sodium, potassium, rubidium and cesium, suitable fatty acids are, for example, caproic, lauric, myristic, palmitic, linolenic, oleic and stearic, and mixtures thereof. Mixtures of acids derived from soybean oil, sunflower oil, safflower oil, cottonseed oil, palm oil and cereal oil are preferred for use herein. Particularly preferred alkaline soaps are, for example, potassium soap from palmitic acid and stearic acid. In addition to alkaline fatty soaps, sucrose mono-, dia triesters of fatty acids are suitable as emulsifiers. Solid mono- and diglycerides may also be used, although they are less preferred.

Although emulsifiers, and especially alkaline fatty soaps, are desirable transesterification reagents, their presence in the polyol polyester product blend is generally undesirable. It is important to remove substantially all the soap from the reaction product prior to thermal evaporation of excess methyl ester to avoid degradation to color products. In addition, a substantial amount of soap, i.e. more than 2000 ppm, causes processing difficulties in forming a dispersion of the unrefined polyol fatty acid polyester with the laundry solution. It is preferred to reduce the soap concentration in the unrefined product to below 2000 ppm, preferably below 1000 ppm, most preferably below 500 ppm, to avoid stable emulsions when dispersing the unrefined polyol fatty acid polyester with the laundry solution. A preferred process for pre-soap removal is to add a small amount of water to the unrefined polyol polyester to cause soap coagulation. Hydration will increase the specific weight of the soap phase, allowing separation. The amount of water is controlled by the amount of soap in the unrefined product mixture. The weight ratio of water to soap is in the range of 1: 1 to 3: 1, more preferably 1.2: 1 to 2: 1, most preferably 1.5: 1 to 1.8: 1. The coagulated soap is removed by a conventional separation process, for example by settling, filtration or centrifugation. As discussed in more detail below, the treated polyol fatty acid polyester, i.e. the polyol fatty acid polyester treated in the mixing vessel with the present process, can be further bleached and / or filtered and further reduced the soap content below the detection limit, i.e. below 50 ppm. The level of soap in the polyol fatty acid polyester can be determined by neutralizing titration with hydrochloric acid or other strong acid to a predetermined end point.

The basic initiator or also the basic catalyst is usually used to initiate the transesterification of the polyol to polyol reaction.

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- 10 fatty acid polyester, at temperatures below the polyol degradation temperature. Although the basic catalyst is an important reactant, it is considered an impurity in the product mixture. Discussion of the types of basic catalysts and their function in the transesterification of polyols can be found in U.S. Pat. No. 3,963,699 to Rizzi et al. and U.S. Pat. Nos. 4,517,360 and 4,518,772, Volpenhein, incorporated herein by reference. A typical catalyst is a strong base with affinity for hydrogen, often referred to as a basic initiator because it serves to transform a stable polyol molecule into a reactive ion. Therefore, the terms basic catalyst and basic initiator may be used interchangeably. The basic catalyst cleaves hydrogen from the polyol molecule and converts it into a reactive state. For example, it converts sucrose into a sucrose anion. Preferred base catalysts are carbonate and methoxide ions that complex with alkali or alkaline earth metals, e.g., potassium or sodium.

The term phase transition catalyst encompasses all chemical compounds interacting with a polyol to form a chemical complex that is capable of switching from one phase to an expensive one, wherein the uncomplexed polyol is normally soluble in the other phase. The phase transfer catalyst as described herein must be distinguished from an emulsifier, e.g. a fatty acid soap, since the emulsifier forms one of the two phases in which all the reactants are soluble, i.e. without the need for complexing. As already mentioned, the phase transition catalyst and also its degradation products, although important for the process of transesterifying polyol to polyol fatty acid polyester, are commonly considered to be impurities in the product mixture.

To reduce the amount of impurities in the blend of the unpainted polyol fatty acid polyester product, the blend of products is preferably treated in a mixing vessel with a wash solution. This operation results in a processed polyol fatty acid polyester. Specifically, the wash solution is fed into the mixing vessel in the opposite direction or in the same direction with the stream of unformed product, or the two solutions are premixed before filling. The term mixing vessel includes any conventional tank, column or other manufacturing device that allows contact between the liquid phases. Examples of suitable mixing vessels are single-deck columns, multi-deck columns, batch tanks, static mixers and bubble columns, and other possible devices are known to the person skilled in the art.

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Multistore columns equipped with agitation are preferred for the present invention. Both columns are suitable for both counter-current and DC-loading and are equally effective for a given droplet size and soap concentration. DC charging is somewhat less effective than counter-feeding with respect to water usage, on the other hand it allows easier operation than counter-feeding. Once the wash solution and the unrefined product mixture are in the mixing vessel, the mixture is mixed and controlled dispersion formation without formation of stable emulsions.

The mixture of unrefined polyester products and the wash solution is preferably maintained in the mixing vessel at a temperature of 20 to 100 ° C, more preferably 40 to 95 ° C, most preferably 65 to 90 ° C. The mixing vessel can operate at reduced, atmospheric and elevated pressure. The advantage of working at elevated pressure is the possibility of a gradual increase in the working temperature, as the boiling temperatures of the components of the mixture increase with increasing pressure. Higher temperatures increase the solubility of the impurities in the wash solution and thereby increase the purity of the purified polyol fatty acid polyester. Thus, the mixing device can operate at a higher temperature without boiling the components. However, the benefits of working at reduced or elevated pressure must be considered in conjunction with other equipment components and the cost of operating at non-atmospheric pressure. From an economic point of view, it is preferable to work at atmospheric pressure.

It is often desirable to prepare a wash solution mixture with an unrefined polyol fatty acid polyester prior to filling into a mixing vessel. The choice of a single inlet device for a stream of a pre-blended mixture of unrefined polyol polyester and a wash solution is more convenient to manufacture, economically advantageous than an alternative solution with two inlets to the mixing vessel.

Further, the unrefined polyol fatty acid polyester can be pretreated and reduced the level of soap impurities prior to filling into the mixing vessel. For example, unrefined polyol fatty acid polyester ⁷ can be centrifuged to remove more than 90 wt. impurities and soaps originally present in the product mixture. As discussed above, it is preferable to remove most of the emulsifier, i.e. soap, if present, thus avoiding the formation of stable emulsions in the wash solution-unrefined polyol polyester fatty acid blend in the blender.

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A preferred preliminary soap removal process is to add a small amount of water to the unrefined product mixture, which promotes coagulation of the soap. Hydration increases the specific weight of the soap phase, which aids separation. The amount of water is controlled by the amount of soap in the unrefined product mixture. The weight ratio of water to soap is in the range of 1: 1 to 3: 1, more preferably 1.2: 1 to 2: 1, most preferably 1.5: 1 to 1.8: 1. The coagulated soap is removed by a conventional separation process, for example by settling, filtration or centrifugation.

After loading the wash solution and unrefined polyol fatty acid polyester into the mixing vessel, the mixture is dispersed at a suitable mixing rate to provide a dispersed mixture, but not a stable emulsion. The mixture, as discussed above, comprises droplets of one phase dispersed in the other. The droplets preferably have an average diameter in the range of 5 to 3000 µm. The composition may comprise washing solution droplets dispersed in an unrefined product mixture, or vice versa, or the composition may consist of both kinds of droplets. The composition of the mixture largely depends on the rate of loading of the individual phases into the mixing vessel, as will be discussed in more detail below.

The dispersion depends, among other manufacturing parameters, on the size and shape of the mixing vessel, the flow rate of the individual components and the type of mixing rate. The term blending includes any type of formation of a mixture of a wash solution and an unrefined polyol fatty acid polyester. Mixing can be carried out by various commonly used techniques and on conventional equipment. For example, dynamic agitation can be accomplished using agitators and rotary disks, acceptable non-dynamic agitation can be accomplished by compressed air (i.e., bubbling), static mixers, and pulsing the mixture stream while filling into the mixing vessel. Mixing with a stirrer is preferred for the present process, although other mixing methods are also suitable for the claimed processes.

Obviously, when using agitators, the rotation speed and shape are significant for the mixing speed and the impurity transition from the unrefined phase. 4 4 4 4 4 4 4 4 4 4 4 4 4 44 44 4 44 44 4

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444444 44 44 44 44 products into the washing solution. The mixing speed can be optimized in terms of forming a suitable dispersion of the composition, undesirable formation of a stable emulsion, massive transfer of soils and soap from the unrefined product phase to the wash solution. As already mentioned, other mixing methods are also suitable for the present process as long as they do not undesirably form a stable emulsion and form a dispersion of the desired droplet size.

The residence time of the mixture in the mixing vessel is also an important parameter in terms of the maximum transition of impurities from the unrefined product phase to the wash solution. The preferred residence time of the mixture in the mixing vessel is in the range of 0.5 to 30 minutes, more preferably 1 to 15 minutes, most preferably 1 to 10 minutes, and can be selected according to e.g. the concentration of impurities and soap in unrefined product. in the processed product.

When a column is selected as a mixing vessel, the number of its trays inevitably affects the residence time of the mixture and the extent of purification. The choice of the appropriate number of trays depends on the height and diameter of the column, the flow rate, the manner and efficiency of mixing, and other operating parameters. If the unrefined product and the wash solution are filled in DC, the number of trays 1 to 7 is preferred. If the filling of the individual phases is counter-current, the number of trays is 5 to 25.

Another important operating parameter that can be optimized in terms of maximum impurity transfer into the wash solution is the amount of wash solution used. The preferred weight ratio of the filled unrefined fatty acid polyol polyester to the wash solution is in the range of 3: 1 to 50: 1, more preferably 4: 1 to 20: 1. More specifically, the weight ratio of the loaded unrefined polyol fatty acid polyester polyol to the loaded wash solution in a DC multistage column is preferably in the range of 3: 1 to 20: 1 and the weight ratio of the filled unrefined polyol fatty acid polyester to the filled wash solution in the opposite direction to a multistore column ranging from 4: 1 to 40: 1.

As mentioned above, a preferred mixing vessel for the present process is a multi-storey column equipped with agitation.

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Multistore columns suitable for the present invention are eg rotary disk extractor, Oldshue-Rushton extractor, Scheibel extraction tower, Kuhni tower, etc. These columns are discussed in Perry et al., Chemical Engineers Handbook, 6th Ed., 1984, p. 21-77 to 21-79, incorporated herein by reference. The columns in Perry et al. are shown schematically in the case of counter-directional filling. The heavier liquid is fed from the top of the vertical column and discharged from below, and the lighter phase is fed from the bottom and removed from above. As already discussed, the streams of the two filled phases may be filled against each other, the so-called counter-fill, or in the same direction, the so-called direct-fill. When both streams are fed at the same end of the column, they are usually drawn at or near the opposite end.

There may be delays between the individual trays within the column, the size and shape of the opening in the tank being adapted to allow the desired residence time in the individual trays according to the operating conditions. Similarly, a stirrer may be connected at each level, typically connected to a single shaft passing through the entire column. Thus, one shaft drives all agitators, ensuring a relatively constant agitation on different trays. On the other hand, devices can be used where the individual agitators have their own independent motor and / or each individual tray a separate gear so that the agitators on the individual trays can move at different speeds. The speed of mixing within the column, in the individual trays, the size and shape of the openings in the trays separating the individual trays and the number of trays are variable parameters that can be optimized for the desired optimization.

Multistore columns may be equipped with quiet zones at both ends where the treated mixture (ie the mixture after sufficient mixing and residence for a sufficient time to the desired degree of impurity transfer into the wash solution from polyol polyester phase to wash solution) is allowed to settle and split into two phases . If the column contains quiescent zones, the resulting phases can be taken from two port extractions, i.e. the first port is used to remove the first phase and the second port to remove the second phase.

After various solutions and process equipment suitable for the present purification process have been discussed, the next possible operation is to further process the treated mixture. The term processing of the mixture includes • 4 49

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A process for removing at least a portion of impurities and / or soap from a polyol fatty acid polyester. Thus, the processed polyol fatty acid polyester is a polyol fatty acid polyester from which at least some of the impurities and soaps have been removed by the present process.

The treated mixture is discharged from the mixing vessel and allowed to settle under two phases under the influence of gravitational forces. Each phase can be separately collected, i.e., the phase containing the treated polyol fatty acid polyester and the phase containing the wash solution, impurities and soap. There are other possible phase separation methods, in some cases more appropriate. For example, if the critical parameter is time and economic considerations less important, the processed mixture can be transferred to a centrifuge where the light phase containing the polyol fatty acid polyester and the heavy phase containing the wash solution, impurities and soap are separated. The polyol fatty acid polyesters treated according to the present invention have a Lovibond red scale value of less than 6, preferably less than 4, most preferably less than 6

2. The lower the value on the Lovibond red scale, the less colored the processed product. The amount of color was determined on a Lovibond Automatic Tintometer with a red-yellow calibration standard (2.9 red / 12.0 yellow).

The processed polyol fatty acid polyester may contain a small amount of washing solution with residual impurities and soap, and vice versa, the washing solution may contain a small amount of polyol fatty acid polyester and other organic substances. Preferably, the treated polyol fatty acid polyester comprises less than 1 wt. impurities and washing solution and less than 100 ppm soap, preferably less than 50 ppm soap. Preferably, the wash solution contains no more than 5 wt. organic oil. Since the polyol fatty acid polyester after processing in the mixing vessel may contain residual amounts of impurities, soap and washing solution, it is advisable to further refine the treated polyol fatty acid polyester in further purification steps. For example, the treated polyol fatty acid polyester may be vacuum dried. This removes the washing solution and flowing impurities. The treated polyol fatty acid polyester can also be filtered through silica gel to remove particulate soap and soap. It is preferred that the treated polyol fatty acid polyester be first dried under vacuum before removing the lower alkyl fatty acid ester so that the concentration of the wash solution, soils, and soap falls below 0.1 wt%. Also, as discussed, it is desirable to include thermal

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Vaporization of a lower alkyl fatty acid tester, if present in the mixture.

The detailed description is further illustrated by examples of aqueous washing of polyol fatty acid polyesters to purified polyol fatty acid polyesters, the concentrations of the resulting product components being tabulated at the end of each example. In the examples, the soap concentration was determined by the titration procedure described above, the color of the product was determined on a commercially available Lovibond color analyzer.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

This example compares the washing process performed on a multi-storey column, the process performed on a packed column, and the process performed in a single-deck mixer with settling. The removal efficiency of soap and water-soluble color materials was compared. Although it is naturally difficult to compare procedures performed on completely different devices under the same operating conditions, at least constant residence times of the purified mixture in the range of 10 to 15 min have been maintained to make the comparison meaningful. All devices were operated at 75-85 ° C. The wash solution was deionized water.

A. Packed column

A column with a diameter of 7.5 cm and a length of 53 cm filled with glass Rashig rings (1 cm) was used. The feed rates of the polyol fatty acid polyester and wash solution were 4.5 kg / L. The mean residence time of the polyol fatty acid polyester and wash solution was 15 min. The polyol fatty acid polyester and wash solution were filled upstream, the top of the column wash solution and the polyol polyester fatty acid from below. The soiled wash solution is collected at the bottom of the column, purified polyol polyester on top. The interface between the wash solution and the polyol fatty acid polyester phase is near the bottom of the column. The droplet diameter was determined to be 3 mm.

• 99 9

99 •

- 99

9 9

9 9

9 9

9

9

9 9 9 • 9 9 9

999 · 9 9 ·

♦ · ··

Β. Mixer with settling

The settling mixer was a round 11 flask equipped with a 5 cm crescent-shaped stirrer. 200 g of unrefined polyol fatty acid polyester and 37 g of washing solution were charged to the flask and mixed in a batch method for 10 min at 150 rpm. The wash solution was dispersed in polyol polyester to a water droplet size with an average diameter of 1000 μιη. Stirring was then stopped. The aqueous phase was allowed to settle at the bottom of the flask below the polyol polyester phase and was decanted from the polyester phase.

C. Multi-storey column

An Oldshue-Rushton column having a diameter of 7.5 cm and a length of 40 cm with seven trays was used as a multistore column. Each tray contained two disc-shaped traps with an inner diameter of 4 cm and height differences between trays ^{7 of} 4 cm. A 4 cm Rushton turbine mixer was mounted in the center of each tray. All agitators were connected to a common shaft rotating at 400 rpm. The feed rate of the polyol fatty acid polyester was 5.6 kg / h and the wash solution was 1.4 kg / h. The mean residence time of the polyol fatty acid polyester and wash solution was 14 min. The polyol fatty acid polyester and wash solution were fed uniformly from the top of the column. The product from the bottom of the column was allowed to settle under the influence of gravitational forces on two phases, the phase of the purified polyol fatty acid polyester and the soiled wash solution. The droplet diameter was determined to be 5 to 70 µm, with an average value of 15 µm.

Table 1 shows the soap content of the wash solution after processing and the coloring of the processed product for each mixer. The best color and soap removal results were obtained in a multi-storey column.

Table 1

Analysis of Polyol Polyester Soap (ppm) Color, AOCS Lovibond Red Grade.

starting material packed column

638

500

4.2

4.0

2.4 l, 8 _ø · * · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · Mixing tank 179

Example 2

This example illustrates the effect of mixing speed on the removal of color in a multi-storey column. The same multistage column as described in Example 1C was used for this experiment, including the same loading rate and flow parameters for both the polyester phase and the wash solution. The column was operated at 75-85 ° C. The starting unrefined mixture contained polyol polyester fatty acids, fatty acid methyl ester, potassium stearate soap, sucrose and water-soluble sucrose by-products, the wash solution containing deionized water. The agitation speed was maintained between 240 and 600 rpm.

Table 2 shows the soap content of the wash solution after processing and determination of the color of the treated product at each mixing rate. The amount of impurities passing from the polyester phase into the aqueous phase increases with increasing mixing speed.

Table 2

Analysis of polyol polyester soap (ppm) staining, AOCS size distribution Lovibond Grade. of droplets

default mat. 638 4.2 240 rpm 218 1,8 400 rpm 161 1,8 550 rpm 110 1.5

15-3000 μιη not determined not determined

600 rpm 98

1,3 9 9 9 9 9 9 9

9 999

9 9

9 9

99 • 9 9

9 9 9 • ···

5-70 μηι

Example 3

This example illustrates the effect of residence time in a mixing vessel on the removal of color in a multi-storey column. The same multistage column as described in Example 1 was used for this experiment. The column was operated at 75-85 ° C. The stirring speed was 500 rpm, the starting unrefined mixture contained polyol fatty acid polyester, fatty acid methyl ester, potassium stearate soap, sucrose and water-soluble sucrose by-products. The wash solution contained 0.5% tri-potassium citrate in deionized water. The feed rate of the polyester phase column was 5.2 kg / h, the wash solution 1.8 kg / h. The mean residence time of the polyol fatty acid polyester and wash solution was in the range of 5 to 10 minutes. depending on the changing number of levels, 3 to 7. The droplet diameter was set at 5 to 70 μηι, the average value being 15 μηι.

Table 3 shows the soap content of the laundry solutions and the determination of the color of the processed product after processing on each tray. The amount of impurities and colored substances passing from the polyester phase to the aqueous increases with increasing residence time in the mixing vessel (with increasing number of trays).

Table 3

Analysis of Polyol Polyester Soap (ppm) Coloring, AOCS

Lovibond red stup.

starting material 638 4.2 5 min, 3 floors 156 2.3 10 min, 7 floors 94 1,8

- 20 00 00 00 00 00 00 00 00 00 00

00 0000 0000

0 0 0 0 000 0 00 · 000

0 0 0 0 0 0

00t 000 00 · 0 ·· 00

Example 4

This example compares the production capacity of a multi-storey column and a single-deck mixer with settling to remove trace levels of iron and calcium from the polyol polyetsre. Each component of the apparatus was operated at a temperature in the range of 75 to 85 ° C. The wash solution was deionized water.

A. Multi-storey column

An oldshue-ruston column with a diameter of 51 cm and a length of 250 cm with seven trays was used as a multi-storey column. Each tray contained two disc-shaped trays with an inner diameter of 26 cm and height differences between trays of 25 cm. A 25 cm Rushton turbine stirrer was mounted in the center of each tray. All agitators were connected to a common shaft rotating at a speed of 50 to 230 rpm. The feed rate of the fatty acid polyol polyester was 1200 kg / h and the wash solution was 210 kg / h. The mean residence time of the polyol fatty acid polyester and wash solution was 2 to 15 min. The polyol fatty acid polyester and wash solution were fed uniformly from the top of the column. The droplet diameter was determined to be 1000 µm. The mixture accumulating at the bottom of the column was separated by a disc centrifuge into purified polyol fatty acid polyester and a wash solution phase.

B. Mixer with settling

A 3300 L tank equipped with a 61 cm wing stirrer was used as a settling mixer. The tank was filled with 1250 kg of unrefined polyol fatty acid polyester and 220 kg of deionized water and the contents were mixed in a batch method for 10 min at 20 rpm. The droplet diameter was set at 3000 µm. Stirring was then stopped. The aqueous phase was allowed to settle at the bottom of the flask and was decanted from the polyester phase.

Table 4 lists the calcium, iron and copper levels for each washed processed product and illustrates that the best results in removing traces of calcium and iron from polyol polyesters were achieved on a multi-storey column. The results for the settling mixer are on average 8

- 21 »» »♦

99 99 9 *

1 2 3 4 5 6 7 8 9 »

9 9 9 9 999 9 9 ·· 999

9 9 9 9 · 9 • 99 999 99 99 99 99 start, for a multi-storey column an average of 4 starts. In both cases, the unrefined starting mixture contained polyol fatty acid polyester, fatty acid methyl ester, potassium stearate soap, sucrose, and water-soluble sucrose by-products. The wash solution contained deionized water without a chelating agent.

Table 4

Analysis of polyol polyester Calcium, ppm iron, ppm copper, ppm mixer 2,51 0.49 0.08 (with settling vessel) column (with stirring) 0.27 0.13 0.07

Example 5

This example illustrates the efficiency of aqueous washing to remove trace amounts of iron, copper, calcium and potassium from unrefined polyol fatty acid polyester. A single 51 cm diameter mixing vessel and a 25 cm Rushton turbine mixer were used. The stirring speed was 230 rpm. The feed rate of the polyester was 1200 kg / h and the wash solution was 210 kg / h. The mean residence time of the polyol fatty acid polyester and wash solution was 2 min. The apparatus was operated at a temperature of 75 to 85 ° C. Deionized water was used as the wash solution. Droplet size ranged from 5 to 70 μηι. The mixture from the bottom of the mixing vessel was separated by a disc centrifuge into a polyester phase and a wash solution phase with dirt and soap.

Table 5 shows the mineral content of the treated polyol fatty acid polyester and shows a significant reduction in levels in the unrefined polyol polyester.

····

• · * ·· ·· ·· ♦ · ·· 99 · · · · 9 9 9 9 9,999 9 9 9 9 9 9 9 9 9 9 9 9 999 · ··· 999 9 9 9 9 9 9 999 999 99 99 99 · - 22 - Table 5 Analysis polyol polyester iron, ppm copper, ppm Calcium, ppm potassium, ppm starting material 0.58 0.14 0.44 20.41 after aqueous washing 0.17 0.06 0.35 0.77

From the knowledge of the presently disclosed purification principles, one of skill in the art may apply other modifications and modifications without departing from the scope of the present invention. Numerous alternatives and modifications have been described and will be apparent to those skilled in the art. For example, the reaction can be successfully carried out in a batch or continuous manner. In addition to the blending devices described, there are other devices useful for preparing sufficiently purified polyol fatty acid polyesters. Polyols and lower alkyl esters of fatty acids have been mentioned as the optimal reaction constituents of the preparation of polyol polyesters, but alternative embodiments can be selected for the preparation of polyol polyesters. The scope of the present invention is given by the following claims, in no way being limited to the illustrative specific examples of preparations and processes.

Industrial applicability

The present invention provides a process for treating synthesized polyol fatty acid polyesters by extracting a crude reaction product with an aqueous wash solution in a controlled mixing vessel. Highly purified processed polyol fatty acid polyesters are useful in the food industry as low calorie fats.

Claims (13)

PATENT CLAIMS CLAIMS 1. A method for purifying an unrefined polyol fatty acid polyester comprising the steps of: a) providing an unrefined polyol fatty acid polyester comprising a polyol fatty acid polyester, preferably sucrose polyester having an average of at least four ester bonds per sucrose molecule, impurities and soap, the soap content is preferably less than 2000 ppm, more preferably less than 1000 ppm; b) feeding the unrefined polyol fatty acid polyester and the scrubbing solution into a mixing vessel, preferably at a weight ratio of unrefined polyol fatty acid polyester to the scrubbing solution in the range of 50: 1 to 3: 1; c) dispersing the scrubbing solution with the unrefined polyol fatty acid polyester onto a composition comprising droplets having an average diameter in the range of 5 to 3000 µm, preferably 5 to 70 µm, for a period of time sufficient to pass at least a portion of impurities from the unrefined polyol fatty acid polyester into the scrubbing solution; preferably for less than 30 min, more preferably less than 15 min; d) separating the blend into a first phase comprising the treated polyol fatty acid polyester and a second phase comprising a wash solution with dirt and soap. The method of claim 1, further comprising the step of discharging the mixture from the mixing vessel prior to separation into two phases. The process according to any one of claims 1 or 2, wherein the dispersion formation step is performed at a shear rate sufficient to form a mixture and not to produce stable emulsions. 44 ·· - 24 ·· * 4 4 4 4 4 4 4 4,444 4,444 4 4,444 · 444 4 4 4 4 4 444 444 44 44 44 · 4 4 4 4 4 4 4 4 4 444 444 4 4 44 44 A method according to any one of claims 1 to 3, characterized in that the washing solution fed into the mixing vessel comprises deionized water. % less than 5.0 wt. % of a chelating agent and less than 0.5 wt. impurities. The method according to any one of claims 1 to 4, wherein the mixing vessel is a static mixer, a bubble column, a mixing tank, a mixing column or a multi-level mixing column. The process according to any one of claims 1 to 5, wherein the dispersion of the wash solution and the unrefined polyol fatty acid polyester onto the mixture is carried out at a temperature of 20 to 100 ° C and atmospheric pressure. The method of any one of claims 1 to 6, further comprising the step of vacuum drying the treated polyol fatty acid polyester to reduce the concentration of the wash solution, soap and impurities to a concentration of less than 0.1 wt%, and a step of filtering the treated polyol fatty acid polyester through silica gel to further reduce the concentration of soils and soap in the polished polyvinyl fatty acid polyester. 8. The method of any one of claims 1 to 7, further comprising the step of removing soap from the unrefined polyol fatty acid polyester by adding water to the unrefined mixture and separating the soap phase prior to filling into a mixing vessel. The method according to any one of claims 1 to 8, characterized in that the weight ratio of water to soap is in the range of 1: 1 to 3: 1, preferably 1.21 to 2: 1, most preferably 1, 5: 1 to 1.8: 1. 10. Processed polyol fatty acid polyester according to any one of claims 1 to 9, characterized in that it comprises a polyol fatty acid polyester and less than 1.0 wt. washing solution and dirt. · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 11. A process for preparing a polyol fatty acid polyester comprising the steps of: a) reacting a mixture comprising a soap, a polyol, preferably sucrose, and a lower alkyl ester of a fatty acid to a mixture of products comprising a polyol polyester of fatty acids, impurities and soap, preferably at a concentration of less than 2000 ppm; b) feeding the reaction product and the scrubbing solution into the mixing vessel in a weight ratio ranging from 50: 1 to 3: 1, preferably 20: 1 to 4: 1, into the mixing vessel; c) dispersing the scrubbing solution and the reaction product onto a mixture comprising droplets having an average diameter in the range of 5 to 3000 μηι, for a time sufficient to pass at least a portion of the unrefined polyol fatty acid polyester impurities into the scrubbing solution; d) separating the blend into a first phase comprising purified polyol fatty acid polyester and a second phase comprising a wash solution of impurities and soap; and (e) phase separation. 12. The process of claim 1, comprising the additional step of pre-removing the soap prior to filling the reaction product into a mixing vessel. 1.3. Process according to any one of claims 11 and 12, characterized in that the weight ratio of soap to water is in the range of 1: 1 to 3: 1, preferably 1.2: 1 to 2: 1, most preferably 1, 1: 1 to 2: 1. 5: 1 to 1.8: 1. A purified polyol fatty acid polyester prepared by the process of claims 1 or 11.